Pressure testing apparatus for bottles

ABSTRACT

A pressure testing apparatus for bottles, comprising a turntable for carrying bottles thereon, pressure-testing heads each supporting vertically movably a pressure-testing piston which, when lowered, moves into a bottle (a) on said turntable from the opening of said bottle and a sealing piston which, when lowered abuts against top end of the bottle to seal the bottle opening, a frame structure supporting said turntable and said pressuretesting heads, and control means for controlling the operation of each of said pressure-testing heads by compressed air in such a manner that said pressure-testing piston is lowered at first and then said sealing piston is lowered and finally said pressuretesting piston is lowered again, said bottle being previously filled with water and, when mounted on the turntable, is positioned immediately below said pressure-testing piston.

United States Patent [191 [111 3,805,594 Hayashi Apr. 23, 1974 PRESSURE TESTING APPARATUS FOR BOTTLES Primary Examiner-Donald O. Woodiel Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT A pressure testing apparatus for bottles, comprising a turntable for carrying bottles thereon, pressure-testing heads each supporting vertically movably a pressuretesting piston which, when lowered, moves into a bottle (a) on said turntable from the opening of said bottle and a sealing piston which, when lowered abuts against top end of .the bottle to seal the bottle opening, a frame structure supporting said turntable and said pressure-testing heads, and control means for controlling the operation of each of said pressure-testing heads by compressed air insuch a manner that said pressure-testing piston is lowered at first and then said sealing piston islowered and finally said pressuretesting piston is lowered again, said bottle being previously filled with water and, when mounted on the turntable, is positioned immediately below said pressure-testing piston.

3 Claims, 10 Drawing Flgures PATENTEDAPRN m4 3.805584 sum 1 [IF 8 I PATENTEB APR 2 3 W4 SHLU 3 UP 8 Q ATENTED 23 1 sum u [1F 8 PATENTEU APR 2 3 ISM SHEET 5 OF 8 QSL H OUTLINE OF INVENTION This invention provides an apparatus capable of rapidly continuously testing the pressure-resistances of bottles for aerated beverages, which comprises a pressure-testing head slidably supporting a small diameter pressure-testing piston adapted to be inserted into a bottle from the bottle opening when moved downwardly and a sealing piston adapted to sealingly close the bottle opening when moved downwardly, and control means for controlling the operation of said pressure-testing head by compressed air in such a manner that the pressure-testing piston is moved down at first and then the sealing piston is moved down and finally said pressure-testing piston is again moved down.

According to the invention, there is also provided a pressure testing apparatus for bottles, which comprises a pressure-testing head having a cylinder, a sealing piston slidably received in the cylinder chamber and being urged in a projecting direction by a spring, and a pressure-testing piston slidably received in an axial hollow of said sealing piston and being urged in a retracting direction by a spring, and which is operative in the manner described above.

BACKGROUND OF THE INVENTION The glass bottles for aerated beverages, presently available on the market, consist not all of new bottles shipped directly from bottle manufacturing plants but include, though at a small percentage, those collected after repeated use, which have flaw's on the surface thereof and are not durable with the gas pressure of an aerated beverage charged therein.

These defective bottles are responsible for the explosion accidents of aerated beverage glass bottles, which are reported from time to time in these days. The explosion accidents possibly result because this type of glass bottles are not included in those which are subjected to control of the regulations on pressurecontainers and, therefore, are shipped from the manufacturing plants after a sampling test only has been performed, utilizing hydraulic pressure, or bottlers use the bottles, including collected bottles, without confirming the strength thereof.

Therefore, in order to prevent the explosion accidents completely, it is necessary to provide in a bottling plant means for testing the pressure-resistance of bottles and to perform a pressure test on all bottles to be used.

The pressure testing means to be provided in the bottling plant for testing the pressure-resistance of each bottle as one step of the bottling process is required to be capable of performing such test rapidly and yet continuously.

Heretofore, a pressure-testing apparatus of a simple construction which fulfills such requirement and is operable with high reliability and less trouble, has not been provided.

DESCRIPTION OF THE INVENTION It is, therefore, an object of the present invention to provide a pressure testing apparatus which is simple in construction and capable of testing the pressureresistance of bottles rapidly continuously and reliably 2 with a minimum percentage of malfunction to meet the requirement set forth above.

Another object of the invention is to provide a pressure testing apparatus which is operated by low air pressure but capable of creating in a bottle a pressure high enough to perform a pressure-resistance test.

Still another object of the invention is to provide a pressure testing apparatus which is operable in a manner to preclude a dangerous condition otherwise caused by the fragments of a broken bottle scattering upon breakage of the bottle during testing.

A further object of the invention is to provide a pressure testing apparatus which has a pressure-testing head of a unique simple construction capable of performing the intended operation.

These objects of the invention can be achieved by a pressure testing apparatus comprising a turntable for carrying bottles thereon, pressure-testing heads each supporting vertically slidably a pressure-testing piston which, when lowered, moves into a bottle on said table from the opening of said bottle and a sealing piston which, when lowered, abuts against the top end of the bottle to seal the bottle opening, a frame structure supporting said table and said pressure-testing heads, and control means for controlling the operation of each of said pressure-testing heads by compressed air in such a manner that said pressure-testing piston is lowered at first and then said sealing piston is lowered and finally said pressure-testing piston is' lowered again, said bottle being previously filled with water and, when mounted on the turntable, positioned immediately below said pressure-testing piston.

. In the operation of this apparatus, when a'water-filled bottle is mounted on the turntableimmediately below the pressure-testing piston, said pressure-testing piston is lowered at first and moves into the bottle from the bottle opening, causing part of the water in said bottle to overflow and therebybringing the. water level to the open top end of the bottle and then the sealing piston is lowered to sealingly close the bottle opening and finally said pressure-testing piston is lowered further, whereby the water sealed in the bottle is pressurized to test the pressure-resistance of the bottle, and upon completion of the testing, the bottle is carried on the rotating turntable to a bottle demounting position. In the bottle demounting position, the pressure-testing head supporting the pressure-testing piston and sealing piston is lifted, so that the bottle is released from engagement with said pressure-testing head and demounted from the turntable.

With this apparatus, therefore, the pressureresistance of bottles can be tested rapidly by hydraulic pressure and the testing is performed on all bottles on the turntable one after another continuously.

To achieve the objects set forth above, according to the present invention there is also provided a pressure testing apparatus of the character described above, in which said pressure-testing head comprises a main body having an air supply port and a cylinder chamber communicating with said air supply port, a sealing piston having an opening communicating with the cylinder chamber of said main body and being slidably received in said chamber, a pressure-testing piston slidably received in said sealing piston with its lower end projecting downwardly from the lower end of said sealing piston and being reduced in diameter at its lower end, a bottle opening-sealing spring urging said sealing 3 piston downwardly and a return spring urging said pressure-testing piston upwardly.

In the operation of this apparatus, the main body of thepressure-testing head is lowered at first so as to move the lower end of the pressure testing piston into the water-filled bottle mounted on the turntable and to bring the lower end of the sealing piston into pressure contact with the bottle opening under the'biasing force of the bottle opening-sealing spring, and then compressed air is supplied into the cylinder chamber from the air supply port, whereby said sealing piston is depressed against the bottle opening with a force equivalent to the sum of the biasing force of said sealing spring and the force of the compressed air acting on said sealing piston, so that the bottle opening is sealed and the pressure-testing piston is forced into the bottle with a force equivalent to the balance of the force of the compressed air acting on said pressure-testingpiston and the biasing force of the return spring, thus creating in said bottle a hydraulic pressure desired for testing. Therefore, it will be understood that the desired hydraulic pressure can be created in the bottle by suitably selecting the proportion between the diameter of the end portion of the pressure-testing piston and the diameter of the portion of the same which receives the compressed air pressure, even when said compressed air pressure is low.

Further, according to this apparatus the testing is effected withwater which is essentially not compressive, so that the testing pressure can be built up easily and, because of water being not compressive, fragments of glass will not fly with force over a wide range, even if the bottle is broken during testing, so that the testing can be carried out with much safety.

The apparatus of the present invention will be described hereunder with reference to practical embodiments thereof shown in the drawings.

DESCRIPTION OF EMBODIMENTS FIG. 1 is a schematic plan view exemplifying the layout 'of equipments in a bottling plant, for explaining the position of the bottle pressure testing apparatus according to this invention;

FIG. 2 is a plan view showing more specifically the position of the bottle pressure testing apparatus of the invention in. the .bottlingplant;

FIG. 3 is a diagram for explaining which element of the pressure testing apparatus is set in operation in what angular position of a bottle, being carried on a turntable of the apparatus, with respect to the center of said turntable;

FIG. 4 is a vertical sectional view showing the details of thepressure testing. apparatus;

FIG. 5 is a vertical sectional view showing the details of the pressure-testing head of the apparatus;

FIG. 6 is a vertical sectional view similar to FIG. 5 but showing the pressure-testing head being in a different operational position;

FIG. 7 is a diagram schematically showing the pneumatic circuit of the pneumatic control device of the apparatus; and 1 FIGS. 8, 9 and 10 are vertical sectional views similar to FIGS. 5 and 6 but showing another type of the pressure'testing head being in different operational positions respectively.

First of all, the layout of a bottling plant to which the bottle pressure testing apparatus of the invention is applicable, will be described by way of example, with reference to FIG. 1. The bottling plant comprises a pallet unloader, an uncaser'2, a bottle washing-machine 3, a bottling and crown fitting machine 4, a stock liquid treating device 5 and a case packer 6, which are relatively arranged as shown and connected with each other by conveyors. The pressure testing apparatus of the invention is disposed between the uncase'r 2 and the bottle washing machine 3 in the manner shown in FIG. 2. Bottles a delivered from the uncaser 2 onto the conveyor are each filled with water during passage through a shower device 7, and fed to the pressure testing apparatus 8, 8.

Now, the construction of the pressure testing apparatus will be described with reference to FIG. 4. The pressure testing apparatus includes a frame structure 9 and a support base 10 which are both fixed on a bed 11. A hollow shaft 12, constituting a main support post of the apparatus, is mounted on the support base 10 integrally therewith, and a turntable l3 and central frames 14, 15, connected integrally with each other, are rotatably supported on the shaft 12 through bearings 16 respectively.

The turntable 13 and frames 14, 15 are driven at a predetermined speed by a driving gear (drive means) not shown, which is in meshing engagement with a gear 17 provided on the turntable 13. A plurality of centering bell units 18 are vertically movably supported on the frame 15, extending downwardly therefrom and are each being urged downwardly by a spring 19. Each centering bell unit 18 has a conical hole-bearing arm 18a at the lower end thereof which is adapted to engage the open end of the bottle a. At the upper end of each centering bell unit 18 is provided a roller R which is in contact with a cam surface provided along the outer peripheral edge of a stationary disc member 20 integral with the shaft 12, whereby the conical hole-bearing arm 18a is moved up and down in timed relation to mounting and demounting of the bottle a. Namely, the conical hole-gearing arm 18a is moved down to secure the bottle a when the bottle has been mounted on the turntable 13 (as shown at the right side of FIG. 4) and is moved up to set the bottlea free upon completion of the pressure-resistance testing. (as shown at the left side of FIG. 4). 1

iA plurality of pressure cylinders 21 are fixedly mounted on the frame 15, each being in pair with each centering bell unit and having a piston rod 22. Each piston rod 22 is provided at its lower end with a pressuretesting head 23, the details of which are shown in FIG. 5.

The pressure-testing head 23 has a main body 36 having a cylinder chamber b formed therein, and a compressed air inlet port 36 is formed in the main body 36 in communication with the cylinder chamber b. A bottle opening sealing piston 25 is vertically slidably receivedin the cylinder chamber b and its downward movement is limited by an internally threaded, flanged stopper 24 screwed over the lower end of the main body 36.

The sealing piston 25 alsohas a cylinder chamber 0 formed therein, and cylindrical stoppers 26, 27 are fixed in the lower and upper portion of said cylinder chamber respectively. A pressure-testing piston 28 is slidably mounted in the cylinder chamber c between the stoppers 26 and 27. The pressure-testing piston 28 has a downwardly extending, small diameter portion 28'. The sealing piston has at its upper end an opening 27 communicating with the cylinder chamber b and is urged to project downwardly by a bottle opening sealing spring 29 and held at the lower end of its stroke by the stopper 24. The pressure-testing piston 28 is urged upwardly by a return spring 30 and held at the upper end of its stroke by the stopper 27. Reference numerals 31, 32, 33 and 34 respectively designate sealing members provided at the sliding portions of the pistons 25, 28. The cylinder chamber 0 is communicating with the outside through a port 25 formed in the lower portion of the pressure-testing piston 25.

Referring back to FIG. 4, the operations of the cylinder 21 and pressure-testing head 23 are controlled by the pneumatic circuit shown in FIG. 7. In FIGS. 4 and 7, reference numeral 42 designates a compressed air supply conduit extending from a compressed air source not shown to the cylinder 21 and pressure-testing head 23.

The conduit 42 leading from the compressed air source is provided therein with an opening and closing valve 37, an air filter 38, an oiler 39 and a regulator 40 (reference numeral 41 designates a pressure gauge) and connected to a rotary joint 43 which is fixed to a ceiling plate 44 of the apparatus, rotatable about the hollow shaft 12 integrally with the frame 15.

The compressed air supply conduit 42 extends further from the rotary joint 43 toward each cylinder 21. Namely, each conduit 42-1 extending from the rotary joint 43 is branched into two lines, one of which extends into the pressure cylinder circuit A and the other one of which extends into the pressure-testing head circuit B. The pressure cylinder circuit A includes a main directional control valve 49 to control the pressure cylinder 21 and pilot valves 45,47 to control said directional control valve 49, said directional control valve 49 and said pilot valves 45, 47 being provided in conduits 42-2 and 42-3 respectively.

The pressure-testing cylinder circuit B includes pilot valves 51, 53 to control the pressure-testing cylinder 23, which are provided in conduits 42-6 and 42-7 respectively. These pilot valves 45, 47, 51 and 53 are respectively controlled by earns 46, 48, 52 and 54 shown in FIG. 7 and 4. Of these earns, the cams 46 and 48 are provided at a test starting position by being supported by a support post 56 and the cams 52 and 54 are provided at a test ending position by being supported by a support post 57. At the test starting position and the test ending position are respectively provided conventional bottle feeding means and bottle discharging means, as exemplified in FIG. 3.

In FIG. 3, reference numeral 58 designates an entrance timing screw for regulating the space interval of the bottles a, being delivered from the uncaser 2, to a predetermined value; 59 a star wheel for feeding the bottles a onto the turntable 13 at a predetermined time interval; and 60 a star wheel for discharging the tested bottles a onto the conveyor extending to the bottle washing machine.

In FIG. 4, reference numeral 61 designates a guard to direct a broken bottle downwardly onto a collecting pan 62 and thereby to prevent the fragments of glass from scattering outwardly of the apparatus; and 63 designates shower means.

The pressure testing apparatus constructed as described above operates in the following manner:

The bottles a delivered from the uncaser 2 onto the conveyor are filled with water during passage through the shower means 7 and successively mounted on the turntable 13 of the pressure testing apparatus one after another, each in a position immediately below each pressure-testing head 23, via the entrance timing screw 58 and star wheel 59 shown in FIG. 3. Mounting of the bottles is effected in the angular positional range A of the turntable shown in FIG. 3, and in this range the cam formed along the outer periphery of the disc member 20 engages the roller R of each centering bell unit 18, causing it to move downwardly, whereby the conical hole-bearing arm 18a of said centering bell unit 18- is moved down to a position slightly above the opening of the bottle a. When the bottle a is shifted to the next angular positional range B shown in FIG. 3, by being carried on the rotating turntable 13, the roller R is moved further downwardly and hence the conical holebearing arm 18a is also moved further downwardly and depresses the bottle opening, whereby said bottle a is secured on the turntable 13.

e The downward movement of the centering bell unit 18 continues until the bottle 0 reaches an angular positional range H of the turntable which will be described later, thereby to hold the bottle a in the fixed state.

When the bottle a is shifted to an angular positional v range C of the turntable, by being carried on the turntable 13, the associated pilot valve 45 is actuated by the cam 46, with the result that the main directional control valve 49 is actuated (this directional control valve is of a memory type and, once actuated, will be maintained in the actuated position even if the actuating signal is 'cut off) and the conduit 42-4 is connected with the compressed air source and further the conduit 42-5 is open in the atmosphere. Consequently, the piston rod 22 and pressure-testing head 23are moved downwardly and the small diameter end 28 of the pressuretesting piston is inserted into the bottle a, so that the water in the bottle a is caused to overflow in an amount just equal to the volume of the inserted end 28" of the pressure testing piston and thus the bottle a is filled with water up to a level flush with the top end thereof.

Such operation is necessary because the water filled in the bottle a by the shower means 7 to the top end of said bottle spills out during transportation of the bottle on the conveyor and the bottle mounting operation by the entrance timing screw 58 and star wheel 59 and, for the testing, the bottle a must be refilled with water to the top end thereof by inserting a volume (the lower end portion 28 of the piston 28) larger than the amount of the spilling water.

The downward movement of the piston 22 stops at the point when the lower end 28' of the piston 28 has been inserted and the bottle a has been refilled with water. At this point, the sealing member 35 at the lower end of the bottle opening sealing piston 25 is brought into yielding contact with the open top end of the bottle through the spring 29, whereby the bottle is sealed preliminarily. In this case, the sealing piston 25 moves up a distance M shown in FIG. 6, relative to the pressuretesting head 23. I

The above operation ends when the bottle a leaves the angular positional range C and then the bottle is shifted into the next angular positional range D shown in FIG. 3. In the angular positional range D and an angular positional range E of the turntable, the pilot valve Slis actuated by the cam 52 and hence the main direc- I tional control valve 55 is actuated by said pilot valve 51 (saiddirectional control valve 55 is also of a memory type similar to the directional control valve 49 and, once actuated, will be maintained in the actuated position even if the actuating signal is cut off), whereby the conduits 42-6 and 42-8 are communicated with each other and air pressure is supplied .to the' pressuretesting head 23. The air pressure thus supplied to the pressure-testing head 23 adds tov the sealing pressure previously given to the sealing member- 35 to cause said sealing member to completely'seal the bottle a. In this case, the positions of the component parts of the pressure-testing head 23 change from the state shownin FIG. to the state shown in FIG. 6. I

Referring to FIG. 6, reference symbol P designates the air pressure supplied to the pressure-testing head 23,.which acts on the piston over its'cross'sectional area which is the balance of the cross sectional area of the outer diameter D, and that of the inner diameter D of said piston, and causes the sealing member 35 to be depressed against the top end of the bottle throughsaid piston 25. (The sealing member depressing force in this case is represented by the formula W+ P X (qr/4) (D D wherein W stands for the biasing force of the spring 29.)

.On the other hand, the air pressure acting on the pressure-testing piston 28 depresses said piston 28 against the biasing force of the spring 30. (The depressing force in this case is represented by the formula P X ('n'/4)D K wherein K stands for the sum of the biasing forceof the spring and the sliding resistance of the sealing members 34.) This means that the lower end 28' of the piston 28, inserted into the bottle, compresses the water filled in said bottle, and from the Pascal's principle, .a hydraulic pressure P [P X ("1r/1,)D,' K]/[(1r/4)D wherein D is the diameter of the'lower end 28' of the piston 28, is created in the bottle 1. Thus, it will be understood that a high hydraulic pressure can be created in the bottle even if the air pressure supplied to the pressure-testing head is low. The value of K, especially the sliding resistance of the sealing members, is almost negligible in thiscase if the air pressure P supplied is determined upon actually measuring the internal pressure of the bottle.

The above-described operation ends when the bottle leaves the angular positional range D of the turntable. However, since'the compressed air is continuously fed to the pressure cylinder 21 and pressure-testing head 23 even after the bottle is shifted into the angular positional range E of the turntable, the hydraulic pressure P is maintained in the bottle a.

In the event when the bottle is small in pressureresistance, it 'is broken by the internal hydraulic pressure. The fragments of glass are prevented from scattering by the guard 61 and led into the collecting pan 62 along with water discharged from the shower means 63 to be collected at one place and discharged to the outside of the apparatus. On the other hand, in the event when the bottle is durable with the internal hydraulic pressure, it is shifted to an .angular positional range F- of the turntable. In this angular positional range, the pilot valve 53 is actuated by the cam 54, with the result that the main directional control valve 55 resumes its originalposition, disconnecting the conduits 8 42-6, 42-8 from each other, and the conduit 42-8 is opened into the atmosphere.

Gonsequently, the piston 28 returns from its lowered position shown in FIG. 6 to the upper end of its stroke shown in FIG. 5, whereby the bottle a is released from the restraining force. The bottle a is further shifted to an angular positional range G of the turntable, whereupon the pilot valve 47 is actuated by the cam 48, so that the main directional control valve 49 returns to its original position, communicating the conduits 42-2 and 42-5 with each other. The pressure-testing head 23 moves upwardly as a whole and thus the lower end 28' of the piston 28 is withdrawn from the bottle a. Then, the bottle a is further shifted to an angular positional range H of the turntable, whereupon the centering bell unit 18 is lifted through the roller R bythe cam formed along the outer periphery of the disc member 44, since said cam is made greater in height in said range, so that the conical hole-bearing arm 18a is disengaged from the bottle opening and said bottle is completely set free on theturntable 13 from the other elements of the pressuretesting apparatus. In an angular positional range I, the tested bottle a is demounted from the turntable and placed on the belt conveyor by the star wheel 60, to be delivered to the next bottle washing station.

Although only one cycle of the pressure testing operation of the apparatus has been described above, it will be understood that, all bottles successively delivered from the uncaser are tested one after another continuously in the manner described.

The filling capacity of a bottling line is usually as high as 1200 bottles per minute but the pressure testing apparatus of the invention is well adaptedfor use in such a bottling line as it is of a rotary type similar to the tiller 4. Furthermore, with thejapparatus of the invention, a testing pressure of 20 kg/cm or even higher can be obtained because air pressure is converted into hydraulic pressure through the pressure-testing head 23 having a unique construction as described above, though the direct use of such a high air pressure tends to result in breakage of the bottles. The use of such pressuretesting head 23 also has made it possible to obtain the desired testing pressure from a low air pressure (on the order of 4 kglcm which is normally used in bottling plants. It is also to be noted that the use of the pressuretesting head 23 and the control circuit of the invention has made it possible to satisfy the requirement for changing the bottle internal pressure by the adjustment.

of the operating air pressure and for obtaining a sealing pressure with said air'pressure.

The bottles fed to the pressure testing apparatus include those which have a chipped open edge and do not enable the testing internal pressure to be built up therein. These defective bottles can be automatically removed from the bottling line by a pressure-testing head of the construction shown .in FIGS. 8, 9 and 10.

7 FIG. 9. In this case, channels 71 formed in the sealing piston 25 are closed by the peripheral surface of the piston 28.

On the other hand, where the bottle is not normal in shape, with its opening edge chipped as indicated at a, in FIG. 10, the testing pressure does not build up in the bottle and the piston 28 moves down until it abuts against the cylindrical stopper 26. Therefore, the channels 71 and 72 are communicated with each other through the annular groove 70 of the piston 28, allowing the compressed air supplied from the compressed air source to flow into a cylinder 74 through said channels 71, 72 and a directional control valve 73, with the result that a piston 75 is projected toward the secured bottle a and instantaneously hits the bottle to remove said bottle from the turntable 13.

The channels 71, 72 are closed again when the pressure-testing head 23 is located in the angular positional range F, because in this range said pressure-testing head is communicated with the atmosphere as described previously and returns to the position shown in FIG. 8. On the other hand, the air in the cylinder 74 is released into the atmosphere through the directional control valve 73 when said directional control valve 73 is re-actuated by a cam 76, whereby said piston 75 returns to its original position.

Although the present invention has been described and illustrated herein in terms of a specific embodiment thereof, it should be understood that the embodiment is merely illustrative and many changes and modifications are possible without deviating from the scope of the invention.

What is claimed is:

l. A pressure testing apparatus for bottles, comprising a turntable (13) for carrying bottles thereon, pressure-testing heads (23) each supporting vertically movably a pressure-testing piston (28) which, when lowered, moves into a bottle (a) on said turntable from the opening of said bottle and a sealing piston (25) which,

' when lowered abuts against top end of the bottle to seal the'bottle opening, a frame structure (14, 15) supporting said turntable (l3) and said pressure-testing heads (23), and control means for controlling the operation of each of said pressure-testing heads (23) by compressed air in such a manner that said pressure-testing piston (28) is lowered at first and then said sealing piston (25) is lowered and finally said pressure-testing piston (28) is lowered again, said bottle (a) being previously filled with water and, when mounted on the turntable, is positioned immediately below said pressuretesting piston (28).

2. A pressure testing apparatus for bottles, as defined in claim 1, wherein said pressure-testing heads (23) each'comprises a main body (36) having an air supply port (36) and a cylinder chamber (b) communicating with said'air supply port, a sealing piston (25) having an opening (27) communicating with the cylinder chamber-(b) of said main body (36) and being slidably received in said chamber (b), a pressure-testing piston (28) slidably received in said sealing piston (25) with its lower end (28') projecting downwardly from the lower end of said sealing piston (25 and being reduced in diameter at its lower end, a bottle opening-sealing spring (29) urging said sealing piston (25) downwardly and a return spring (30) urging said pressure-testing piston (28) upwardly.

3. A pressure testing apparatus for bottles, as defined in claim 1, wherein there is provided defective bottle removing means (74, 75) for removing a defective bottle from the turntable (13), which comprises a channel (71) bored through the small diameter lower end of the pressure-testing piston (28) and a compressed air passage to be formed through said channel (71) when said pressure-testing piston (28) is in its lowest position. 

1. A pressure testing apparatus for bottles, comprising a turntable (13) for carrying bottles thereon, pressure-testing heads (23) each supporting vertically movably a pressure-testing piston (28) which, when lowered, moves into a bottle (a) on said turntable from the opening of said bottle and a sealing piston (25) which, when lowered abuts against top end of the bottle to seal the bottle opening, a frame structure (14, 15) supporting said turntable (13) and said pressure-testing heads (23), and control means for controlling the operation of each of said pressure-testing heads (23) by compressed air in such a manner that said pressure-testing piston (28) is lowered at first and then said sealing piston (25) is lowered and finally said pressure-testing piston (28) is lowered again, said bottle (a) being previously filled with water and, when mounted on the turntable, is positioned immediately below said pressure-testing piston (28).
 2. A pressure testing apparatus for bottles, as defined in claim 1, wherein said pressure-testing heads (23) each comprises a main body (36) having an air supply port (36'') and a cylinder chamber (b) communicating with said air supply port, a sealing piston (25) having an opening (27'') communicating with the cylinder chamber (b) of said main body (36) and being slidably received in said chamber (b), a pressure-testing piston (28) sLidably received in said sealing piston (25) with its lower end (28'') projecting downwardly from the lower end of said sealing piston (25) and being reduced in diameter at its lower end, a bottle opening-sealing spring (29) urging said sealing piston (25) downwardly and a return spring (30) urging said pressure-testing piston (28) upwardly.
 3. A pressure testing apparatus for bottles, as defined in claim 1, wherein there is provided defective bottle removing means (74, 75) for removing a defective bottle from the turntable (13), which comprises a channel (71) bored through the small diameter lower end of the pressure-testing piston (28) and a compressed air passage to be formed through said channel (71) when said pressure-testing piston (28) is in its lowest position. 